It is a city composed of the towns of Maipo, Viluco, Linderos, Valdivia de Paine, Alto Jahuel, Los Guindos and El Recurso.

According to the 2002 census of the National Statistics Institute, Buin spans an area of 214.1 km2 (83 sq mi) and has 63,419 inhabitants (31,440 men and 31,979 women).

[2] As a commune, Buin is a third-level administrative division of Chile administered by a municipal council, headed by an alcalde who is directly elected every four years.

[1] The communal council has the following members: Within the electoral divisions of Chile, Buin is represented in the Chamber of Deputies by Ramón Farías (PPD) and José Antonio Kast (UDI) as part of the 30th electoral district, (together with San Bernardo, Paine and Calera de Tango).

The commune is represented in the Senate by Guido Girardi Lavín (PPD) and Jovino Novoa Vásquez (UDI) as part of the 7th senatorial constituency (Santiago-West).